Insulation in Homes

Insulation, in the construction industry, is defined as something which is used to insulate a building or a home. Insulation performs two functions: reducing the loss of heat from the home to the outside cold weather and reducing the gain of heat from the hot summer air outside the home. It is basically a material used to maintain the temperature differential between the interior and exterior of the home.

Proper insulation is an important energy (and money) saving factor for any home. Insulation ensures that your heater or your air conditioner isn’t constantly running.

A home has plenty of “weak points” through which air from within the home can leak outside and air from outside can flow into the home. Some examples of these points include electrical outlets, attic space, rim joists, holes in walls, windows, doors, and any crawl space. Such weak points can result in energy loss and sub-optimal house temperature.

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Types of insulation

There are three main types of insulation that homes tend to have in them:

Foam Insulation

Foam can provide high R-values, but it can also cost a lot. There are two types of foam insulations commonly used. First is the injection foam. This kind of foam insulation can be pumped into walls, cavities, and any existing spaces. Existing homes and structures are great use-cases for this kind of foam insulation.

The second type of insulating foam is spray foam. As the name suggests, this material is sprayed in open areas and cavities, attic spaces, crawl spaces, and rim joists. The foam is available in liquid form. There are two types of spray foam, open cell and closed cell. Open-cell foam is light and shifts as it dries and settles. Closed-cell foam is a lot denser. It is heavy and is more resistant to temperature as well as weather changes.

Fiberglass Insulation

Fiberglass insulating material is available in rolls and batts. It can be fitted between joists, beams, and studs. It can also be placed in ceilings, floors, and unfinished walls. Fiberglass insulation is made up of plastic. The plastic is reinforced by tiny glass fibers. The glass fibers improve the insulating capacity of the plastic while making it stronger.

Cellulose Insulation 

Cellulose insulation can be used in open new wall cavities or in enclosed existing walls. Unfinished attic doors are also another use case for cellulose insulation. This type of insulation can be blown in or loose-filled. Cellulose insulation is mainly made up of recycled paper fiber. Besides paper, ammonium sulfate, boric acid, and fire retardant are used. Cellulose insulation can also be sprayed.


The R-value of an insulation material represents its ability to resist heat flow. The higher the R-value, the stronger is the insulating ability of the material. The R-value of an insulating material depends on the material itself, its density, and its thickness. Other factors like moisture accumulation, aging, and temperature also affect the R-value.

Increased insulation thickness by installing more insulating material increases the R-value of the insulation. For multi-layered insulation installation, the R-value of the entire insulation is the addition of the R-values of each individual layer.

The way the insulation is installed also affects its R-value. For example, insulation that is compressed will not result in the same R-value that the material is rated for. The use of studs, joists, and other such materials allows heat to flow through them. This phenomenon is known as thermal bridging.

R-value and Energy Efficiency

The R-value’s impact on energy efficiency is quite significant. A higher R-value means that the insulation works that much harder to prevent heat transfer. Less heat loss (or heat gain if the weather is hot) will mean lower utility bills. Your heater or air conditioner will have to work that much lesser and the energy consumption will be lower.

You may be surprised to know that a staggering 50 to 70 percent of the energy consumption for a standard US home is due to heating and cooling. These are the official numbers provided by the US Department of Energy. Therefore, any savings on energy bills is a significant win.

The majority of older US homes have insulation with an R-value of 13. Newer standards call for using R-19 insulation. Roof R-values are generally 30 or 40.

2X4 vs 2X6 Wood for Exterior Walls

There are two main types of wood sizes used to build the exterior walls of a house, 2X4 and 2X6. A 2X6 configuration offers greater depth of wall cavities, which technically means that you can add more insulation and increase the R-value. However, most builders typically do not add extra insulation when you use a 2X6 setup. Generally speaking, 2X4 walls use insulation up to R-13 or R-15 while 2X6 walls use insulation up to R-19.

However, you must also consider the unintended consequences of using more insulation. Using too much insulation is actually not a good thing. Some types of insulation like fiberglass work effectively when there are air pockets that provide thermal resistance. Air pockets trap the warm air in them. Cramming in too much insulation reduces these air pockets. Spray or rigid-foam insulation works well in such cases because the air pockets are already pre-existing in such types of insulation.

There are two main ways in which you can increase the insulating efficiency of your 2X4 walls. Either go to the thicker 2X6 walls or add exterior insulation to your existing 2X4 walls.

We hope that you now have a basic understanding of how insulation works and what the different types of insulations are. If you are looking to build new construction in South Bend, IN or the surrounding areas (New Carlisle, Granger, Mishawaka) please check out our current homes under construction as well as our floor plan library.

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